My Homemade PC-Based "Coal Trol" and Stoker Control Theory

WissaMan · Post by **WissaMan** » Fri. Sep. 25, 2009 1:06 pm

Here's a pic of the "stove server" status screen. Note the stove isn't burning right now (still a tad too warm to fire 'er up...hopefully this weekend

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Stove control status screen

.JPG | 65.2KB | status window.jpg

ErikLaurence · Post by **ErikLaurence** » Fri. Sep. 25, 2009 7:13 pm

WissaMan wrote:Cool, I'm glad I'm not the only person that's had these kinds of ambitions. My wife says it "must be a guy thing" to want to "control" stuff I realize I could have a coaltrol and have more free time, but I enjoy the challenge of a project like this, which is well suited for winter time since I can't work on any outdoor projects...

I actually have this system working, so I'm past the theory stage. I am currently using an older HP PC (<1ghz) as a dedicated controller running a fresh, clean install of XP. XP is actually pretty stable as long as you don't have tons of stuff installed on it (though if I had the knowledge, I'd rather do it with a Linux...but alas) As for some of your other concerns...it will not have internet connectivity so auto updates/reboots are no problem. Currently my program is set to load at startup so if there is a power failure, the PC will reboot automatically and with only the OS loading, it boots to desktop in under 30 seconds. All important variables are written to disk every time the program cycles through the control loop, so upon reboot the program can "pick up where it left off". Though all that asided, a UPS is in my long-term plans.

The interface I use is a Phidget (http://www.phidgets.com) which has digital and analog inputs and digital outputs and connects to the PC via USB. That is really the key piece to my setup and w/o that I wouldn't be able to do this. The second key piece is that I was able to use the Phidget C+ API with Clarion (Clarion is a somewhat obscure, but very powerful language I program in and is the only language I have any skill in these days). I do think that Arduino piece looks nice and if I wasn't already commited with this particular setup, I probably would consider it. Another setup I did consider was using MS Robotics Studio, but after my initial tests with Clarion were successful, I abandoned that idea quickly since it would've meant learning a whole new language.

Regarding the blower control, I am using the Phidget interface to turn the fans and pusher motor on and off using solid-state relays I pulled from old copiers (which are a treasure trove of components ) I don't plan on trying to modulate the speed of the fans, only turn them on/off for variable periods of time. I think the Phidget interface can turn on/off it's outputs pretty quickly so theoretically I could control the speed by turning them off/on rapidly but I'm not sure that would be good for the motor. Old copiers also have a multitude of 24v DC fans which could be modulated by voltage but unfortunately, Phidgets does not make an interface with analog outputs so I currently have no way of controlling devices other than with on/off.

eelhc, I do plan on using a thermal probe to regulate the stove temperature, however my goal is to regulate it in relation to the outside temperature (as well as the inside) and run the distribution blower constantly. I feel like if the stove is producing heat and I'm not utilizing it, then it is being wasted, so I'd rather lower the stove temperature when less heat is needed and keep the blower constant than vice versa. Although I may change that idea once I install the DHW coil.

Cheers,
Wissaman

Phidgets are awesome.

Get a couple of the pressure sensors and you can monitor draft on your dashboard too.

jfgovern · Post by **jfgovern** » Fri. Sep. 25, 2009 7:55 pm

Good for you! Very cool project - I actually had the same thought last month after speaking with Coal-Trol and learning that they don't have a product for boilers yet. Sounds like you're off to a good start - one consideration I'd throw into the fray would be to analyze what the worst-case failure state would be, and then develop a mitigation plan (i.e. combustion-blower and feed get latched-on, stove over-heats with no relief) - might want to consider running an over-temp thermal-switch set above the regular maximum-temperature switch already on the stove which would trip in a run-away situation and cause the fire to extinguish safely. Not sure exactly how to stop a run-away on your particular stove, but something to consider. Hate to come home and find the house on fire with the computer in "blue-screen-of-death" mode with all output relays latched closed.

If you haven't looked already there's a TON of parts for sale cheap on e-bay for these types of projects as well - lots of used A/B controllers, PID units, sensors, etc... You might also consider posting the project on Sourceforge.net - may be others in the open-source community who are intersted and would help you develop the code. Keep us posted on progress!

WissaMan · Post by **WissaMan** » Mon. Sep. 28, 2009 6:27 am

jfgovern, that's a good point about the non-PC safety -- I'll have to get one of those clicky buttons like the drier's use. I think another thing I could do is write a small monitoring program to run on one of my other PC's. It could check the log file and if it detects the log file is not getting updated (because of crash) it will send an email to my cell phone. I know, getting even more complicated

ErikLaurence, that's a cool idea! I noticed there are two kinds of Phidget pressure sensors -- one is a "differential" sensor, I assume that is the one I would use to monitor draft. The other one it says can be used to measure atmospheric pressure. I should get one of those too. I already have an outdoor temp sensor, I might as well add barometer so I can have my own little remote weather station...

WissaMan · Post by **WissaMan** » Fri. Oct. 30, 2009 1:40 pm

Hi Folks, I just figured I'd update you on how my system has been working out. I have had to make some tweaks and add some extra control properties since my original design. The main thing that was causing me trouble was how the nights were chilly but the days were warm (in the 60's).

But overall, it has been working well. With a steady outdoor temperature, it can usually hold the indoor temperature almost dead on -- no more than a few tenths of degree F variation. Typically the system seems to keep the temperature between .1 and .4 degrees above the setting. In cases where the outdoor temperature drops quickly, it can sometimes "fall behind" since it can take a while for the stove to heat up if it's been idling for a while. The worst I have seen it "caught off guard" has been about -.5 degrees below the setting. I am considering writing code to help predict heating demand based on the slope of the curve of the outdoor temperature, but I'll wait until it gets colder to see if that's really necessary.

I wrote a graph window so I could visually "see what's going on" (see pic). I won't go into totally explaining everything on the graph, but if you look to the top you'll see what each colored line represents. Also, you may notice I'm using Remote Desktop to access the control PC -- I'm actually at work, about 20 miles away from home. So if I really wanted, I could put the chill on the 'ole wifey and turn the temp down on her

Yanche · Post by **Yanche** » Fri. Oct. 30, 2009 9:28 pm

WissaMan, I just got a chance to look at the Phidget web site (http://www.phidgets.com/) Some really interesting hardware gadgets. Especially interesting to me is the Single Board Computer (SBC). Looks like it's the same 8 analog input, 8 digital input, 8 digital output interface you are using. That would make a real nice stand alone controller that also would have connectivity to a PC via Ethernet. Especially impressive is the programing libraries that come with the products. The thermocouple sensor interface is especially nice. Phidget's products are most complete the shelf inexpensive data acquisition products that match my AHS boilers needs. It could be the basis for a complete boiler controller. Replacing the aquastat, ash temperature sensor and adding many more features like outdoor temperature reset, BTU measurement, out fire detection, etc. I'll put one on my Xmas wish list.

WissaMan · Post by **WissaMan** » Sat. Oct. 31, 2009 8:14 am

Yeah, Phidgets are awesome! I just looked up that SBC too, they must've just introduced that. That certainly would be sweet, having the complete system be on a single board w/o all the potential failure areas of a PC (hard drive, power supply, loose cards, etc. etc.) and I know Linux can't be beat for stability (I run two homemade Smoothwall (http://www.smoothwall.org) firewalls which are Linux-based and they are rock solid). Sadly, I don't have the knowledge to develop applications for Linux

But so far, Windows has been stable--no crashes. I think it's because I don't have it loaded up with all kinds of apps and stuff and the only drivers I have installed are the ones that came with windows (i.e. generic drivers for video, sound, etc.). I have the control software running as a service now and the computer is set to auto turn on in BIOS, so if I have a power flicker it'll come back up on it's own (this happened once so far). I still have yet to put it on a UPS but that is in my plans.

I'll be very interested to hear about your project so please keep us posted!

BlackRockBurner · Post by **BlackRockBurner** » Fri. Nov. 06, 2009 10:35 pm

Funny thread. I'm just finishing up building a MicroLogix 1000 PLC based control system for my Keystoker 90k. I'm using 2 pair of BCD thumbwheel switches to control idle feed time on and off and maybe cycle the combustion blower on and off during idle also. Used a few math functions into a N7 file to modify the BCD values into 10's for the left switch and 1's for the right, multiply times 60 to convert to seconds and move the value into a T4 timer. When the thermostat calls for heat it shuts down the idle timer logic and runs full out. I'm using the original over temp safety switch as an enable, and use the room air switch as an input and control all the motors through the PLC using 24v outputs to switch Crydom 10A SSR's. The PLC and controls will be mounted on the wall in the garage with 2 cables (3 conductor 18ga 24v input and 4 conductor 14ga 110v output) run to the stove. The room thermostat will be run to the PLC. All totaled I'll have about $100 into the whole system, bought most of the parts off of ebay. Will post pic's if anyone is interested.

Mark

europachris · Post by **europachris** » Sat. Nov. 07, 2009 9:56 am

I plan on building up a PLC based control for my EFM/Iron Fireman bituminuous boiler setup based around a CuBloc PLC: http://cubloc.com/product/03_02cusb22d.php since I already have one. It's a really neat controller that can be programmed in ladder or BASIC or even a combination of both.

However, it does not have thermocouple or RTD inputs, and the outboard converter is pretty expensive. So, I plan to use an Automation Direct PID temp controller and use it to signal the PLC for heat and also use the alarm outputs for under/overtemp, etc. It should make the programming simple, too.

It would probably be just as easy to do it with a handful of relay sockets and relays......but not as fun.

Chris

AdkCoal · Post by **AdkCoal** » Sat. Nov. 07, 2009 11:18 pm

DVC500 at last wrote:
Bratkinson wrote: COBOL, FORTRAN and PL/I. I lost count of how many assembler languages and databases I’ve learned and forgotten… (4 different 14xx IBM models I used way back in the mid-late 60’s each used a variation of Autocoder, and then came the 70xx boxes….). Bottom line, there’s a learning curve just to get everything ‘talking’.
Well your talking my language now I still remember coding the cc tapes for the 1403's when I was in the AirForce. Installed a BASIC compiler on the 360 system. Mostly wrote in Fortran IV, later in SAS, lator wrote the IODFs for the mainframes. HCD was a nice improvement over the old card-image setup. That was a LONGGGG way from today's Z/OS systems (which I love!)
Yep, I'm still happy with the controller in my DVC-500. Thats why I bought it. I have no interest in Over-designing something that probably wouldn't do a better job anyway.

Wow.

Two other system guys on this forum . The IBM 1403 was the first machine that I ever wrote code for using 1403 Autocoder.
Eventually wound up working for Digital Equipment Corporation and wrote device drivers in VAX/VMS assembler and PDP-11 Macro Assembler.
Seems we are cut from the same cloth.

Back to the subject of this thread.

I use a boiler so CoalTrol won't work for me. What I need is an electronic timer to replace the mechanical timer on my Keystoker KAA-2. It annoys me to no end to be in the boiler room and hear the stoker shut down and look and see that the water temp is at max and then hear it kick back on again because the timer kicked in. Would rather have an electronic timer that has enough sense to know that the stoker had just shut down and would skip the current set point that just triggered. Do not have the time to create the beast though.

BlackRockBurner · Post by **BlackRockBurner** » Sun. Nov. 08, 2009 1:24 am

europachris wrote:However, it does not have thermocouple or RTD inputs, and the outboard converter is pretty expensive. So, I plan to use an Automation Direct PID temp controller and use it to signal the PLC for heat and also use the alarm outputs for under/overtemp, etc. It should make the programming simple, too.

It would probably be just as easy to do it with a handful of relay sockets and relays......but not as fun.

Chris

Yea, the MicroLogix 1000 doesn't have any analog inputs either, I'm just going to use it for timing and switching. I was also thinking about using a counter to see how many times the thermostat calls for heat and an RTO to tally up the total time it's on, this way I may be able to write a routine to anticipate the heat and stop the coal feed early to reduce the heat cycling some more. Last year I burned just shy of 4 tons of coal, and the house was always very warm, 75deg +, due mainly to the poor idle control offered by the mechanical controls (Hugh heat cycles) . Saving a half ton of coal or more would just about pay for the system in the first season. I have a Stainless Steel RTD and an Athena controller that I could use to monitor the exhaust temp and provide inputs to the PLC, but for a little hot air stoker, the timed functions should be fine. (lol, famous last words?

)

Mark

Highlander · Post by **Highlander** » Sun. Nov. 08, 2009 9:29 am

I use a small PLC built by Crouzet to control my boiler. It is their Millenium 3 model, and has the ability to handle analog as well as digital inputs. http://www.crouzet.com/millenium3/html/en/home-en.htm They are inexpensive controls, and have programmable backlit display that can be used for monitoring and modifying different parameters. They program using a graphical function block language that allows for offline simulation and online monitoring as well.

My system monitors the boiler water temp as well as outdoor temp and uses this to vary the stoker on/ off duty cycle as needed. The PLC also keeps track of coal usage based on stoker run time. A separate temperature control monitors the flue gas temp and sends a signal to the PLC if it falls below a preset value which would indicate an outfire.

Your PC based control project is really cool, and you can generate some interesting trends and charts with a PC. I do not see too many PC based process or machine controls in my work, the general industry trend is towards PLC's or embeded microprocessor designs for long term reliability.

The Micrologix 1100 is good PLC, I have programmed several machines around them. Some of them are upgradeable with analog input modules and you could use a small text or graphic HMI for an operator interface. Parts are readily available on Ebay, especially for Allen Bradley PLC's.

WissaMan · Post by **WissaMan** » Tue. Nov. 10, 2009 12:20 pm

Highlander wrote:I do not see too many PC based process or machine controls in my work, the general industry trend is towards PLC's or embeded microprocessor designs for long term reliability.

Yeah, I realize that and I wish I had the know-how to pull this off with either a PLC or a Single-board-computer like that Phidget device mentioned above, but unfortunately I have no experience with PLCs or programming in Linux so they both would require a ton of new learning on my part.

I know the PC is a complicated piece of hardware with a lot of potential failure points (power supply, hard drive, motherboard, etc. etc. etc.), but one thing I have observed, and this may sound crazy, but in my experience if something on a PC is going to fail, it usually happens within about the first 3 years. It seems like if they get to that point w/o failing, they can go on almost forever...

BlackRockBurner · Post by **BlackRockBurner** » Tue. Nov. 17, 2009 1:31 pm

The MicroLogix system is up and running. I'm working on setting the proper idle feed times.
The green light in the bottom left tells when it's calling for heat, the white light is when it's idling.
The red pushbutton will blink if the stove ever hits the high temp limit until it's pushed to reset the alarm, so I know
what the stove is doing when I'm away. The switch turns the system on and off, and the two sets
of BCD thumb switch's are for the feed motor on and off time during idle. I mounted the system in the
laundry room about 10ft from the stove and ran two cables over to it. One for the 24v inputs and
the other for the 110v motor feeds. Each cable has a few spares in it in case I want to expand my
inputs or outputs in the future. Here's a Pic..

Mark

europachris · Post by **europachris** » Tue. Nov. 17, 2009 1:48 pm

BlackRockBurner wrote:The MicroLogix system is up and running. I'm working on setting the proper idle feed times.
The green light in the bottom left tells when it's calling for heat, the white light is when it's idling.
The red pushbutton will blink if the stove ever hits the high temp limit until it's pushed to reset the alarm, so I know
what the stove is doing when I'm away. The switch turns the system on and off, and the two sets
of BCD thumb switch's are for the feed motor on and off time during idle. I mounted the system in the
laundry room about 10ft from the stove and ran two cables over to it. One for the 24v inputs and
the other for the 110v motor feeds. Each cable has a few spares in it in case I want to expand my
inputs or outputs in the future. Here's a Pic..

Mark

That looks great, Mark! Wanna come work for me and rewire some PLC cabinets that look like a truck full of Spaghetti-Os crashed into them?

My Homemade PC-Based "Coal Trol" and Stoker Control Theory

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